Example of interruptible tasks in action
In the illustration below, tasks A, B and C are linked together. Note that there are two links from task A to task B: a Start-to-Start link and a Finish-to-Finish link:
If none of the tasks are designated as interruptible tasks, the tasks would look as follows after a reschedule:
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The tasks are in the same position as they were prior to the reschedule, even though the Start-to-Start link from task A to task B indicates that task B could start earlier. |
If task B is designated as an interruptible task, the tasks would look as follows after a reschedule:
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The duration of task B, the interruptible task, is increased: task B is stretched so that both of the links from task A are straightened during the reschedule. The schedule now accurately shows that task B can start at the same time as task A. |
Note that if any of an interruptible task's constraining links are deleted, the interruptible task will revert back to its original duration - it will 'unstretch', as illustrated below:
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Start-to-Start link removed |
Finish-to-Finish link removed |
Interruptible tasks and milestones
You may want to turn an interruptible task into a milestone in order to remove its effect from your project plan. If you turn an interruptible task into a milestone, the milestone retains the interruptible status of the task. If you subsequently reschedule your project, the reschedule ignores all incoming Finish-to-Finish and Start-to-Finish links that lead to the interruptible milestone, so that the milestone can be positioned in the project plan as early as possible. You can turn an interruptible milestone back into a task by increasing its duration.
If task B in the above example is turned into a milestone, the tasks would look as follows after a reschedule:
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Task B, the interruptible task, is positioned as early as possible in the project plan. Note that this can result in backwards-sloping links, as illustrated to the left. |
